Bi-amp with same sort of amp?

Talked to a man today about my loudspeaker project(that never gets ready).He ment that it´s preferable to use the
same type of amps for the subs and the rest of the system.
According to him, using different types of amps, with different slew-rates ("speed" -if you want) often ends up in a mess.
I use Volt 12" woofers, in separate enclosures, and I will run them up to about 65 Hz,only, using a VMPS electronic crossover(only low-pass filtering). I will use a 8" and two 3.5" Accutone ceramic drivers and an Eton ER 4 tweeter per channel.
Having built some speakers in my days, this is my first time
using an electronic crossover for Hi-Fi.(I used the word bi-amp for convenience, in the title).
Any opinions are welcome!

Håkan in Sweden
I think it depends on whether you are biamping vertically or horizontally. For vertical biamping (bridging amp to mono) I would recommend staying with the exact same amps. If you are talking horizontal biamping, one amp fo bass the other for the mids and highs, I disagree. I have found that using amps from different manufacturers with different slew rates and different power outputs to not be a problem. I've used less expensive, more powerful amps like an Adcom (200wpc)on the bass, then driven the mids/highs with a lower powered Classe/ Counterpoint (100wpc) or such with very good results. I hope this helps.
Reason for asking is that I have experienced different
timing or pace in the same music, when listening to different amplifiers. E.g. I have a 100 w Class A amp
which is somewhat slower in the lower register, than
my home-built monoblocks, all are solid state ones.
The monoblocks have real good ability in the bass region,but as I built them more than 15 years ago(and although I have updated them), I dare not use them with the new speakers and in the long run, because of risk of ampfailure,which could be costly as this loudspeaker-project isn´t a cheap one.
(So, they may retire in the bedroom system).

Like you , I thought that I could buy a cheaper amp for the
subs(consider my loudspeakers as a sub- satellite system).
But I may rethink the idea of using different amps in the system. And that because I´m very sensitive to the pace of the music.
On the other hand, using top-class amps even for
the lower register, will cost a lot of money.

(I have played some music myself- if that matters).

So, if I state my question more clear,can you say that the
more complex a system gets, the more unpredictable it becomes. From that followes, that the possible combinations
of amps and cables and room treatment, whith a complex system,may never be optimized. Or, that at least it will take a very lot of time to get near your goal?
And are there some more experiences and opinions to this matter?
Of course,even if someone has failured, while trying to
combine different amps for bass, mids, and treble, in a synergetic way, please let me know!

I have actually used amps to compensate for slew rates damping factors etc. I'm biamping Martin Logan Monoliths with Levinson Reference 20.0 monoblocks on top. They are what I would call "dark" amps. Very smooth, very refined--relatively low damping factor. They really sound good on the panels and have no problems with the impedance loads. On the bottom end I'm using Krell KMA 160. A bit more powerful, higher damping factor. These have better control in the bass end. For me, my speakers benefited from using different amps--and I selected the amps to do just this--but different speakers would certainly have different requirements, benefits, and drawbacks. It is nice to be able to taylor the amp individually for the low vs the high. I'm not very familiar with the VMPS--I have heard them--but that's all.
it is generally more difficult to match differing amps for bass & mid/treble. that said, as abstract7 points out, it *can* be done, but ya have to pay close attention to the characteristics of the speakers & the amps.

using an active crossover, w/adjustable wolume for at least one of the amps, makes things a lot easier. my current system uses a pair of larger vmps subs, crossed-over at 60hz, to a pair of meret re monitors. these monitors have an eton carbon-fibre woofer & a focal inwerted-dome tweet. i use a pair of bridged adcom gfa-555's to drive the vmps', & a pair of electrocompaniet aw60ftt's in a wertical-biamped set-up to drive merets. i have *no* problems w/the different amps, because the 60hz crossover point is effected w/a marchand 24db/octave active x-over. besides offering separate bass & treble wolume controls, it also offers a wolume control *at* the x-over point. this makes it easy to match differing amps w/differing slew & gain rates. i highly recommend using an active x-over in general, and for transparency at a reasonable cost, i feel the marchand can't be beat. while i don't have direct experience w/the well-regarded bryston 10b, for example, more than one person told me the marchand is more transparent, at half the price. the marchand is also more flexible, imho...

hope this helps, doug s.

I forgot to mention the crossover. This probably plays a big factor in whether the biamp will sound good or not. Some speakers bass crosses over to the mids at 200 or 300 hz. This might be too high, where the difference in amps is more audible. I think the lower the crossover frequency the less impact using different amps will have. For the record the speakers I were biamping have the crossover set at 120 hz. From this point down I think it's okay. The higher frequencies will start to enter lower midrange area where you might notice the amps not matching more easily.
The biggest concern for me ,because I'm looking to do the same sort of thing, is gain matching. Forget about vertical or horizontal etc. If one manufacturers amp requires more voltage than anothers, there will be volume differences that will throw the whole presentation off. You can use outboard crossovers that will settle that issue, but at what cost? If you like what company A is doing for you at the top of the band, then use one of their amps for the bottom as well. If you like tubes on top and solid state at the bottom, then you have to use an outboard crossover for gain variations. This combo can be phenominal or horrible. Always be careful when puttin' on the chefs' hat.
Well, I carried out an experiment yesterday. I connected
one channel of the big class A amp to a full-range speaker,
the other speaker was connected to one of my homebuilt mono-blocks. Yes, the amps in question have different gain,and one inverts the signal and the other does not.They also have
different tonal characters, and as I mentioned before, to me
they have different timing or pace, especially in the lower register.
The result of the study: it didn´t sound good at all!
I tried to be open-minded when listening, but the sound was
confusing, in my ears. Interesting is, that I used one of
the monoblocks together with a smaller monoblock for a period(as I was updating the other home-brewn monoblock),and while they too had different gains(my tube preamp doesn´t have abalance control), the result was quite nice!And, to me, those amps have almost the same pace in their presentation.
The VMPS electronic crossover that I own, has gain as well
as attenuation,for each cannel, therefore different gain
in the amps that I will use for the lowest register, and the rest of the system, should not be a problem.

I think I begin with a good amp for the upper register,
i.e. from about 65 Hz and uppwards. Then I will try different amps for the lowest register, thus checking if the
registers blend together.Patmatt,I fully agree to your last sentence!

Thanks for the response! I've just recently purchased a pair of the Monarchy SE100 Deluxe amps, and I'm very satisfied with their performance. I was using a Muse model 160 before, which is also excellent, but nowhere near as open as the Monarchys'. At $1200.00 for the pair (used 10 mos.), I couldn't resist. I'm thinking of Bi-Amping with the Muse on the bottom, so I'm very interested in how your results turn out. Thanks for the info about inverting/non-inverting. I can't believe I overlooked that issue. ROOKIE MISTAKE!
A friend of mine has bi-amped his b&w monitor with an acurus amp for the highs and an adcom for the lows.
This is one incredible combination!
The imaging is as engaging as any I have ever seen.
The music comes through as if the stereo has been replaced by the artist!
Experiment as much as you can.This is fun!
Good luck.
I am using a 15 year old amp and have friends with 30+ year old amps. I would not think twice about using the homebrew amp if you can make them work! In most cases the sub is the "slowest" of the speakers. The larger cone has more mass, so it is harder to start and stop. An amp with a high damping factor and a lot of current reserve should help to bring synergy to your system.
My previous speakers were NHT 2.9s. I used an NHT SA-3 subwoofer amp on the bottom end with Atmasphere M60 mk2's on the top. The NHT sub amp has a volume control. I now have Legacy Signature IIIs for speakers and I will be experimenting with two SA-3s on the bottom end. To me this is the best of both worlds - solid state with volume control on the bottom and tubes on the top.